High power hydraulic control systems for an electric switch

ABSTRACT

The invention relates to hydraulic control systems for operating movable members, particularly of electric switches, which require large instantaneous forces. A functional assembly includes power members such as an hydraulic jack, inlet and purge valves, and a high pressure oil source. The hydraulic linkages of this assembly are subject to high pressure and high flow rate and are formed directly in the connecting surfaces of the members, i.e., without conduits. An operational assembly for controlling the functional assembly can be connected thereto by conduits of relatively small cross-section as these conduits will not be subject to high pressure, or high flow rate and thus the length of the conduits for remote control does not present any of the usual problems associated with high pressure control systems.

United States Patent I I 33 w! I I i I I I I I 1 lil S Gratzmuller 1 Oct. 16, 1973 4] HIGH POWER HYDRAULIC CONTROL 1,309,328 10/1962 France 200/82 B SYSTEMS FOR AN ELECTRIC swrrcn 131813985 6/1959 France 1,098,565 8/1955 France [76] Inventor: Jean Louis Gratzmuller, 66 1,230,514 9/1960 France 200/82 B Boulevard Maurice Barres, NeulnYsurseme France Primary Examiner-Robert K. Schaefer Filed: 3 1971 Assistant Examiner-Robert A. Vanderhye [21] AppL No: 197,809 Att0rneyHerbert l. Cantor et al.

[30] Foreign Application Priority Data [57] ABSTRACT Nov. 23, 1970 France 7041926 The invention relates to hydraulic control systems for [52] Us. Cl. e 200/82 B operating movable members, particularly of electric [331 3.3. CI..111111111111111111111'33311;"33733110I3 33/33 ewieeeee whieh require leeee A [58] Field of Search zoo/s2 B 148 F mama] mcludes pwer members as ZOO/148 E 82 R 148 92/28 an hydraulic ack, lnlet and purge valves, and a high I pressure oil source. The hydraulic linkages of this assembly are subject to high pressure and high flow rate [56] References cued and are formed directly in the connecting surfaces of UNITED STATES PATENTS the members, i.e., without conduits. An operational 2,408,1 9 9/194 Cu m ng et a1 ZOO/82 B X assembly for controlling the functional assembly can 3,345,487 l0/l967 Stl'Om 200/82 B X b onnected thereto conduits of relatively small 2,813,177 11/1957 Eberhard et al. 200/82 B X cross section as these conduits i not b Subject to 1 gig' high pressure, or high flow rate and thus the length of 2:900:469 8/1959 fi'fi' ZOO/82 B the conduits for remote control does not present any 3,133,475 5/1964 Barkan 200/82 B x the usual Problems asscmated wlth Pressure control systems. FOREIGN PATENTS OR APPLICATIONS 1,350,707 12/1963 France 200/82 R 3 Claims, 2 Drawing Figures l I 4 46 40 I PATENTEDum 1 6 I975 SHEET 2 [IF 2 B Miil/ BACKGROUND OF THE INVENTION This invention relates to a high power hydraulic remote control system and in particular to hydraulic control systems for electric switches.

Standard hydraulic controls consist in essence of the following elements: at least one hydraulic power device, generally a jack, which operates the member to be controlled, such as the movable contact in a switch;

members forming the source of pressurized hydraulic in the form of applications and releases of hydraulic 2 pressure; and means for sending orders or controls which transform low power orders,'generally transistory electrical orders, into hydraulic orders which are applied to the valves.

PRIOR TECHNIQUES The most frequent arrangement has hitherto comprised mounting the operating jack directly on the device being controlled, to ensure the shortest possible mechanical transmissions, and grouping the hydraulic control equipment in a chest or in the form of an operational block, easily accessible, which was connected to the jack by one or more feeding/purge lines sometimes several meters in length.

.The power and the speed of response required of hydraulic controls are continually increasing, in the case of switches because of the ever increasing electric power loads transported by the grid systems.

In order to increase the power of hydraulic controls withoutproportionatelyincreasing their size and price,

it is at present necessary to use hydraulic pressures much higher than in the past, in the same way as the voltage of electrical distribution lines have increased. Thus some years ago it was usual to provide hydraulic controls operating at a pressure of 200 or 300 bars (1 bar 0.987 normal atmospheres about 1.02 Kg/cm"); the pressures used nowadays are of the order of 600 to 1000 bars, without the feed rates having been reduced.

For the control of high tension and very high tension switches, especially in the case of self-blowing switches, it is necessary to develop considerable instantaneous power, which creates serious problems in the transmission of hydraulic energy through conduits several meters long and joints subjected to high pressures, sensitive to hydraulic hammer and producing charge losses. Up to the present time these inconveniences were only of slight importance at the pressures normally used.

OBJECTS AND SUMMARY OF THE INVENTION The object of the present invention is to overcome these difficulties, which with high power hydraulic controls arise from the increase in operating pressures and in particular from'the considerable problems posed by the provision of joints.

The term functional members" or power members" will be used below to designate the members which provide the distribution of high pressure hydraulic energy, produced by a hydraulic station, and the transformation of this energy into mechanical energy capable of operating the mechanism being controlled.

The terms operational members or control members will designate the members such as pilot electrovalves which transform low power electric impulses into hydraulic orders, of high pressure but low feed rate, which are applied to the functional members.

According to the present invention there is provided a high power hydraulic remote control system including a plurality of functional members, a plurality of operational members, and a hydraulic station for supplying said members with hydraulic fluid under high pressure, at least those functional members which are likely to be subjected to hydraulic fluid at high pressure and high flow rate being grouped together in a block in the form of a functional assembly wherein the hydraulic linkages are made through connecting surfaces of said functional members by large cross-section orifices, with no interposed conduits, and the'hydraulic linkages between the functional assembly, the hydraulic station and the operational members, which linkages may be of greater length than those of the functional assembly, being provided by low power conduits.

In an hydraulic control system as provided by the invention, the operational members, preferably grouped as an operational assembly, may be common to several functional assemblies which may be quite distant, e.g., several metres, from the operational assembly.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

' FIG. 1 is a schematic representation of an hydraulic control system in accordance with the invention, as ap-' plied to a switch; and

FIG. 2 is a detailed view of one of the functional assemblies, or power assemblies, used in a control system in accordance with the invention.

DESCRIPTION OF THE INVENTION FIG. 1 shows a high power hydraulic control system for operating three single-pole switches 2, 2', 2" whose movable contacts 4, 4', 4" are operated by hydraulic jacks 6, 6', 6" respectively, of functional assemblies 18, 18, 18" of the control system. Since the functional part of the hydraulic control is identical for each switch, and is shown in greater detail in FIG. 2, only the functional assembly 18 which concerns the switch 2 will be described.

In accordance with the invention this assembly includes at least the jack 6, a piloted hydraulic inlet valve 8, a source of high pressure oil such as an oleopneumatic accumulator 10, and a hydraulically piloted purge valve 12. The functional assembly 18 preferably also includes an intermediate low pressure reservoir or tank 14.

In accordance with the invention all these functional or power members are directly fixed to each other, in the form of an assembly, with no interposed conduits.

Thus the accumulator 10 is affixed directly to the body of valve 8, itself fixed to head 16 of jack 6. Also fixed directly on head 16 is the purge valve 12 to whichin turn is attached the tank 14.

Each functional assembly 18, or power assembly, is thus mounted directly on the equipment, such as a switch, which is to be controlled.

Each of the accumulators 10, 10" is charged with high pressure oil by a respective conduit 20, 20, 20" with these conduits being connected by a conduit 22 to an hydraulic station 24 which may be a certain distance (several meters) from the functional assemblies.

The hydraulic station may include a pump P which draws water from a low pressure reservoir 25 and forces it into the conduit 22, with a buffer accumulator 27 possibly mounted in parallel.

The inlet valves 8 and purge valves 12 for the functional assemblies receive hydraulic orders emitted by order-sending members, or operational members, which in FIG. 1 have been represented simply by the electro-valves 26, 26', 26" and which are grouped in an operational assembly 28 which may be several metres away from the functional assemblies 18, 18', 18" and connected thereto by conduits 30, 30, 30". Conduits 31, 31', 31" connect the inlet valves and the purge valves together.

In accordance with the invention, the only conduit which have an appreciable length are-those through which oil passes at-a low rate, and consequently these conduits may have a small cross-section, with no inconvenience even if they are of long length.

Thus the conduits 20, 20', 20", 22 need only transmit the amount of oil needed for recharging the accumulators, and this recharging takes a very long time in relation to the operating time forthe jacks 6, 6, 6". Similarly, and as will be seen below, the conduits 30, 30", 30" for sending hydraulic orders only have to transmit pressure impulses (or pressure relief rm pulses), with scarcely any movement of oil, to operate the inlet valves 8 and purge valves 12. Finally the intermediate tanks 14, 14, 14" are connected to themain tank 25 by conduits 32, 32', 32" ofquite small crosssection and low pressure, since the emptying of the intermediate tanks can be effected relatively slowly, between two operations, under atmospheric pressure or at most a small extra pressure.

' Due to the grouping of the power members in accordance with the invention, there are no conduits under high pressure and with high flow rates; the only lengthy hydraulic linkages are those with a low flow rate and which can be made of small cross-section.

An installation in accordance with the invention will now be described in more detail, and in particular the functional or power assembly 18 in such an installation.

The driving member in this assembly is the hydraulic jack 6. This jack may be a single-action jack acting against return means, such as resilient return means. In FIG. 1 it was assumed that the jacks-6 were single- 1 action jacks acting by pushing.

In FIG. 2 there is also shown a single-action jack, but one acting by traction, i.e., its shaft 34, extended by an insulating shaft 36, operates the movable contact of the switch by means of a standard motion-reversing mechanism, not shown (bell crank, rack and pinion, or the like). As a variation the jack 6 may be a double-acting jack or a rotary jack.

The source of high pressure for the power assembly is preferably the oleopneumatic accumulator 10 whose cinity of the driving jack, without any interposition of long conduits or connections. To aid clarity in the drawing, the relative volumes of the jack and the accumulator have not been truly represented. In practice the volume of the accumulator would'be several times greater than that of the jack. Acalibrated jet 40 may be used to control the rate of feed of oil from accumulator 10 towards the jack 6 to control the speed of displacement of the jack piston 42 in operating direction.

Since the invention applies especially to high pressure hydraulic controls (above 300 bar), it is particularly advantageous to use oleopneumatic accumulators 10 whose gas compartment 44 is filled with gas such as.

helium which has a low coefficient of thermal expansron.

As a high pressure source for the power assembly, one can naturally also use a spring hydraulic accumulator, a high feed rate, high pressure pump, or a hydropneumatic accumulator with a projecting rod such as described in French Patent 1,181,985.

The direct connection. of the accumulator 10 on the inlet valve 8, and of the valve 8 on the jack head 16 is effected for example by screws, not shown, which compress sealing members 46 and 48. Similarly the purge valve 12 is directly connected to the jack head 16; a calibrated jet 50 may be interposed between these two members to control the purge rate of the jack and hence the speed of piston 42 during its return movement. I

A high power functional assembly in accordance with the invention may comprise only the four main members just described: High pressure source (oleopneumatic accumulator), inlet valve, power jack, and purge valve. In this case outlet 52 of the purge valve should be connected to a conduit of large cross-section and relatively long length taking the purged oil to the main tank 25. This conduit would have to provide passage for a large flow rate, but at low pressure, which would'not therefore create any particular difficulty; it

'is however preferable to add to the functional assembly the low pressure intermediate reservoir 14 which is directly attached to the purge valve 12. This intermediate reservoir 14 can be emptied relatively slowly, between two operations of the jack, by the low pressure and low cross-section conduit 32. A non-return valve 54 permits air to return into the reservoir 14 when this empties, this valve being preferably disposed as described in French Patent 1,345,674.

In a modification, the intermediate reservoir 14 may be replaced by low pressure hydraulic accumulators, of various types, such as with a spring, a gas cushion, a bladder, a-membrane or a blower.

After the accumulator 10 has first been charged with oil under pressure by the conduits 20 and 22, which as stated have a cross-section corresponding only to the relatively low -outputra'te of pump P, the operation of the installation is as follows.

The functional assembly 18 receives an operating order from the operational assembly 28, in the form of an emission of oil sent by one of the control electrovalves 26 through the conduits 30 and 31 towards the valves 8 and 12. These types of feed and purge valves,

forming an hydraulic relay, have been described in French Patent 1,181,985. Since the volume of oil needed to move a piston 56 in the inlet valve 8 and to open an inlet valve 58 is small, the conduits 30 and 31 need have only a small cross-section. An obturator 60 in purge valve 12 remains on its seat while valve 58 is opening, which enables the accumulator to feed pressurized oil to jack 6, this feed taking place over a very short path, with a large cross-section, with no conduit or pipe-joint.

The piston 42 moves, impelled by the oil, and, when the control system is used with a switch, engages the switch in closed position, for instance against a disengagement spring.

According to the schematic representation of the operational assembly in FIG. 1, as long as the electrical order to the electro-valve 26 is maintained, the corresponding hydraulic order remains applied to the valves 8 and 12, and the switch remains engaged.

In practice, known operational assemblies of more advanced type are naturally preferred, especially those of the self-maintaining" type, for which the electrical orders for operation (engagement or disengagement) are only transistory, and which perform various other monitoring and security functions.

In order to perform the reverse operation, i.e., disengaging of the switch, then, in FIG. 1, it is sufficient to release the pilot pressure in the conduits 30, 31, while electrically ordering purging of electro-valve 26.

With the pilot pressure released, the obturator 60 rises and puts the jack into communication with the intermediate tank 14, where the oil under low pressure is temporarily accumulated before returning via the small cross-section conduit 32 to the main tank 25, from where it is drawn by pump P.

The operational assemblies which may be used in an installation in conformity with the invention, in place of the simplified assembly shown in FIG. 1, maybe of the most varied types. Thus one may use a single-path assembly with hydraulic self-maintenance, having an open center main valve, of the type described in French Patents 1,098,565 and 1,281,356. An assembly including an inlet valve and a purge valve, as described in French Patent 1,185,054, may also be used, with the valves controlled by an electro-magnetic inlet valve and an electromagnetic purge valve, as described in French Patent 1,098,565.

In a variation of the above arrangement, the two said electromagnetic valves may be mounted directly on the inlet and purge members in the functional assembly, which permits a reduction in the times for sending orders.

In an installation in accordance with the invention it is important for the small cross-section conduits, especially the conduits 30, 31 for sending hydraulic orders, to be free of air, to ensure speed and simultaneously transmit orders. This is why the conduits are preferably supplied with automatic air-purging means, for instance of the type described in French Patent 1,230,514.

The invention is naturally not limited to the embodiment shown and described: it is capable of numerous variations available to those skilled in the art, according to the intended applications, while remaining within the scope of the invention.

I claim:

1. An hydraulic remote control system including a cylinder having an operating piston reciprocable therein, said cylinder being provided with an inlet port to admit liquid under pressure to one face of the piston to drive the piston in one direction, said cylinder having an outlet port to remove the pressure liquid from the one face of the piston, a remote controlled admission valve, said admission valve having a casing provided with inlet and outlet ports, said casing being secured to the cylinder with the inlet port thereof in axial alignment with the outlet port of the casing, a remote controlled exhaust valve, said exhaust valve having a casing provided with inlet and discharge ports, said exhaust valve casing being secured to the cylinder with the outlet port thereof in axial alignment with the inlet port of the exhaust valve casing, 21 hydropneumatic accumulator having a pressure liquid compartment provided with an inlet port and an outlet port, the accumulator being secured to the admission valve casing with the outlet port of the pressure liquid compartment in axial alignment with the inlet port of the admission valve casing, a main pressure liquid reservoir, a source of liquid under pressure connected to the reservoir, an auxiliary reservoir having an inlet port and an outlet port, the auxiliary reservoir being secured to the exhaust valve casing with the discharge port thereof in axial alignment with the inlet port of the auxiliary reservoir, first conduit means connecting the inlet port of the pressure liquid compartment of the accumulator to the delivery side of the source, and second conduit means connecting the outlet port of the auxiliary reservoir to the main reservoir.

2. The hydraulic control system according to claim 1, in which said admission valve comprises a movable valve actuating member operable in response to liquid pressure to cause opening of the admission valve and in which said exhaust valve comprises a movable valve actuating member operable in response to liquid pressure to cause closing of the exhaust valve, said system further including third conduit. means connecting the valve actuating member of the admission valve and the valve actuating member of the exhaust valve in series to said discharge side of the source, and electromagnetically operable valve means in said third conduit means for controlling the flow of pressure liquid from the delivery side of the source to said series connected valve actuating members.

3. The system according to claim 1 wherein said piston operates a movable contact of an electric switch. 

1. An hydraulic remote control system including a cylinder having an operating piston reciprocable therein, said cylinder being provided with an inlet port to admit liquid under pressure to one face of the piston to drive the piston in one direction, said cylinder having an outlet port to remove the pressure liquid from the one face of the piston, a remote controlled admission valve, said admission valve having a casing provided with inlet and outlet ports, said casing being secured to the cylinder with the inlet port thereof in axial alignment with the outlet port of the casing, a remote controlled exhaust valve, said exhaust valve having a casing provided with inlet and discharge ports, said exhaust valve casing being secured to the cylinder with the outlet port thereof in axial alignment with the inlet port of the exhaust valve casing, a hydropneumatic accumulator having a pressure liquid compartment provided with an inlet port and an outlet port, the accumulator being secured to the admission valve casing with the outlet port of the pressure liquid compartment in axial alignment with the inlet port of the admission valve casing, a main pressure liquid reservoir, a source of liquid under pressure connected to the reservoir, an auxiliary reservoir having an inlet port and an outlet port, the auxiliary reservoir being secured to the exhaust valve casing with the discharge port thereof in axial alignment with the inlet port of the auxiliary reservoir, first conduit means connecting the inlet port of the pressure liquid compartment of the accumulator to the delivery side of the source, and second conduit means connecting the outlet port of the auxiliary reservoir to the main reservoir.
 2. The hydraulic control system according to claim 1, in which said admission valve comprises a movable valve actuating membEr operable in response to liquid pressure to cause opening of the admission valve and in which said exhaust valve comprises a movable valve actuating member operable in response to liquid pressure to cause closing of the exhaust valve, said system further including third conduit means connecting the valve actuating member of the admission valve and the valve actuating member of the exhaust valve in series to said discharge side of the source, and electromagnetically operable valve means in said third conduit means for controlling the flow of pressure liquid from the delivery side of the source to said series connected valve actuating members.
 3. The system according to claim 1 wherein said piston operates a movable contact of an electric switch. 